Emergence of NETCONF

We'll start this post off with a quick intro on Netconf and bit more detail about Netconf.

What is Netconf ?

NETCONF is a protocol that was developed to provide a standardized interface to Network Devices to retrieve and manipulate configuration data.

The Network Configuration Protocol (NETCONF) is a network management protocol allowing a Network Automation Platforms (e.g. NSP from Nokia) to Create, Modify, and Delete configurations of network devices. Standard application programming interfaces (APIs) are available on network devices for the Network Automation Platforms to manage the devices using NETCONF.

NETCONF uses Extensible Mark-up Language (XML)-based data encoding for the configuration data and protocol messages and uses a simple remote procedure call (RPC) mechanism to implement communication between a client and a server. A client can be a script or an application running on an Network Automation Platforms. A server is typically a network device.

Most of the Network Engineers are familiar with the CLI then this definition will strike you as nothing new. And you wouldn't be wrong - the main Goal of both NETCONF and CLI is to provide an interface for configuration on Network Device. The main difference between the two interfaces is that they are both designed and optimised for very different applications and purposes.

The CLI aims to provide humans with a very user-friendly means for interacting with a device. Commands are very readable, easy to remember and have no painful syntactic requirements.

NETCONF, on the other hand, was designed for automation Platforms. It uses a clearly defined XML API that computer programs may interface to with ease. The NETCONF protocol may be broken down into four distinct layers as illustrated in the diagram below.

Why Do We Need NETCONF?

Now a days Network automation is one of the main requirements for ISP/CSP's, including fast and on-demand Intent Based Service Provisioning / Infrastructure Provisioning and automatic OAM with service provisioning. However, this requirement cannot be met by the conventional network management methods: command-line interface (CLI) and?Simple Network Management Protocol?(SNMP). This is where NETCONF comes in, which is gaining momentum in network automation. most of network automation platform now using Netconf to do provisioning of infrastructure / services / OAM.

Disadvantages of CLI and SNMP

CLI-based configuration is complex and differs greatly according to vendors. CLI is not vendor agnostic, Nokia, Juniper, Cisco all have different CLI Structure.

CLIs vary significantly by vendor, so users have to learn and develop adaptation scripts for each vendor's CLI. Additionally, frequent changes to the CLI structure and syntax make it difficult to maintain CLI scripts.

The output of commands is structure-agnostic, unpredictable, and prone to changes, causing great difficulties in automatically parsing CLI scripts.

SNMP does not support the transaction mechanism, resulting in a low configuration efficiency. Therefore, it is typically used for monitoring purposes.

SNMP uses the User Datagram Protocol (UDP), which cannot provide reliable and ordered data transmission and lacks an effective security mechanism.

SNMP does not have a mechanism for submitting configuration transactions. Therefore, configuration is performed separately for each object serially, not for each service. When multiple objects need to be configured, unknown impacts may be caused on the network if some objects are successfully configured and some fail to be configured.

SNMP manages device configuration on a per-device basis and does not support network-level configuration or multi-device configuration collaboration.

Emergence of NETCONF

XML Based Netconf introduced to overcome the disadvantages of CLI and SNMP, There are many advantages using Netconf Over CLI and SNMP

·??????NETCONF uses a hierarchical protocol framework, making it more suitable for on-demand, automated, and big data requirements of cloud-based networks.

·??????NETCONF uses XML encoding to define messages and uses the RPC mechanism to modify configuration data. This facilitates configuration data management and interoperability between devices from different vendors.

·??????NETCONF performs operations on devices based on the?Yang Models, reducing network faults caused by manual configuration errors.

·??????NETCONF provides security mechanisms such as authentication and authorization to ensure message transmission security.

·??????NETCONF provides a transaction mechanism to support data classification, storage, and migration, phase-based submission, configuration isolation, as well as overall configuration delivery, verification, and rollback, minimizing the impact on network services.

·??????NETCONF defines a variety of operation interfaces and supports extension on basis of capabilities. This allows vendors to define their own protocol operations, so as to implement unique management functions.

How Does NETCONF Work?

Architecture of NETCONF

A NETCONF system contains at least one Automation platform that manages network devices. The following figure shows the basic network architecture of NETCONF.

The NETCONF architecture is client and server model

·??????A client provides the following functions:

·??????Manages network devices using NETCONF.

·??????Sends RPC requests to a NETCONF server to query or modify one or more parameter values.

·??????Learns the status of a managed device based on the alarms and events sent by the NETCONF server of the managed device.

·??????A server maintains information about managed devices and responds to the client-initiated requests.

·??????When receiving a request from a NETCONF client, the NETCONF server parses the request and sends a reply to the client.

·??????If a fault or another type of event occurs on a managed device, the NETCONF server reports an alarm or event to the client through the notification mechanism. This allows the client to learn the status of the managed device.